Patent GB-980241-A (GB)
Title: Hydraulic operating device for a vehicle clutch
IPC: B60K23/02
Filed: 1963-07-25
Abstract: 980,241. Controlling clutches. BELTOMATIC PATENTVERWERTUNGSANSTALT. July 25, 1963 [July 25, 1962], No. 29437/63. Heading F2L. A vehicle clutch K is engaged by an hydraulic servomotor S under the influence of pressure regulated in accordance with the position of an accelerator pedal 22 and increased above a predetermined output speed of the vehicle, and is disengaged automatically upon gear shift. The servomotor piston 6 is biased to its disengaging position by a spring 8 stronger than the clutch engaging springs 9, and the pressure in the working chamber 5 is regulated by a valve V having a diaphragm 12 controlling connection between the supply line and a'return pipe 10. The accelerator pedal 22 is connected by a rod 21 and a spring 20<SP>1</SP> to an intermediate member 20 fast with a piston 18<SP>1</SP> which is operatively connected by a spring 17 to a piston 19 bearing on the valve diaphragm 12 so that depression of the accelerator pedal loads the valve diaphragm. The pistons 18, 19 are mounted in the interior of a plunger core 16 associated with a weak, lowresistance solenoid 13 and a strong, highresistance solenoid 14 which are connected in series in a circuit leading from the vehicle batteries 23, the ignition switch 24 and a further switch 25 which serves to disable the automatic device, to the solenoid 13, and the junction between the solenoids 13, 14 is connected through a switch 26<SP>1</SP> closed on operation of the gear-change lever 26 to earth. The solenoid 14 is also connected to earth through a centrifugal switch 27 which is closed at a vehicle speed of about 10 kilometres per hour. On starting with the switches 24, 25 closed and the accelerator released pressure in the servomotor S is low and the clutch is disengaged. As the accelerator pedal is depressed the valve diaphragm 12 is loaded and the servo pressure rises giving initial clutch engagement. When the centrifugal switch 27 closes both solenoids 13, 14 are energized and the plunger core 16 is moved downwardly and acting on the piston 18 by way of a stop 16<SP>1</SP> compresses the spring 17 to load the diaphragm 12 to give a minimum servo pressure irrespective of the accelerator position. Further depression of the accelerator pedal will continue to increase the servo pressure till the full clutch engaging pressure is obtained. On actuating the gear-change lever 26 the switch 26<SP>1</SP> is closed so that the solenoid 14 is shorted out and the full current flows through the low-resistance solenoid 13 which raises the core 16 and hence the piston 19 to free the valve diaphragm and cause a sudden drop in the servo pressure to disengage the clutch. The switch 25 for disabling the automatic device is connected by a cable to a pawl 29 which when the automatic device is operative engages a notch 30 of a detent part 31 to hold the servomotor cylinder stationary. When the switch 25 is operated to disable the automatic device, the pawl 29 releases the servomotor cylinder and the clutch can be disengaged by the clutch pedal 32, the servomotor moving as a whole with movement of the pedal 32. The clutch can however also be disengaged by the clutch pedal 32 when the automatic device is in operation.